PROJECT SUMMARY/ABSTRACT The study of human diseases at the molecular level has benefitted greatly by rapid advances in technology for genome sequencing. However, impediments for effective utilization of current and future genomic information relates to challenges associated with functional assignment of genes. The field of proteomics has arisen to help address this need, since proteins are the predominant functional molecules in cells. Measurement of proteomic content, including protein expression levels, posttranslational modifications and protein interactions can yield critical insight relevant to gene function. The major challenges in proteomics research relate to the complexity of samples and the wide dynamic range over which measurements must be performed. In general terms, these demands are far greater than encountered in genomics since, protein abundances can vary much more than genes do, proteins have much wider diversity in physical properties than genes do, and proteins have no means for signal amplification, nor analogous Watson-Crick base pairing as genes do. Thus, the field of proteomics employs technology largely based on mass spectrometry measurements of peptides since these measurements have shown capabilities for large-scale protein identification and quantitation. However, since each protein can produce on average, 50-100 peptides, measurements of peptide mixtures are far more complex than measurements on proteins. In addition, current data-dependent measurement strategies lead to significant compression of achievable dynamic range, since such MS/MS measurements are only normally feasible on peptides observed with higher abundance. Ideally, every peptide in a proteome-wide digest would be subjected to MS/MS to gain maximal information from proteomics experiments. This project will advance capabilities for large-scale proteomics through the development of a mass spectrometer array capable of high resolution MS/MS acquisition an order of magnitude faster than current state-of-the art technology. The MS array technology to be developed under this project will involve ion cyclotron resonance mass spectrometry that will yield higher mass resolving power, higher mass measurement accuracy as well as higher throughput acquisition. As a result, an order of magnitude or more peptides can be identified during a given experiment which will dramatically increase the information content of each proteomics analysis as well as the dynamic range of proteins that can be studied.